Embodiments of the present disclosure generally relate to ultrasound probe assemblies, systems, and methods, and, more particularly, to ultrasound probe assemblies, systems, and methods that are configured to reduce air entrapment, such as would otherwise exist between a delay line and a structure being inspected.
Ultrasound probes are used in various settings. For example, certain ultrasound probes are used to detect damage within various structures, such as portions of aircraft. Lightweight composite materials are used in the aerospace industry for both commercial and military aircraft and other aerospace vehicles, as well as in other industries. Composite structures may be formed using multiple plies or layers of material that may be laminated together to form a high strength structure. The structures may undergo further machining processes during manufacturing and assembly of vehicles (drilling, cutting, countersinking, shimming, fastener removal, etc.), as well as further processes related to flight and ground operations (maintenance, repair, retrofit, or overhaul).
Ultrasound probes may be used to scan structures (such as composite or metal wings, fuselage, and the like of an aircraft) to assess a condition of the structure. For example, if a dent or scuff mark is evident on a portion of an aircraft, a handheld ultrasound probe may be used to determine the existence of sub-surface damage.
A typical ultrasound probe includes a housing that contains a single element transducer. Other known ultrasound probes include multi-element transducers, in which ultrasound elements are arranged in a two-dimensional matrix. The multi-element ultrasound probes are able to produce a spatial C-scan of a small area (such as a dent or hole damage location) with a single placement of the probe. Such probes are commonly referred to as “ultrasonic cameras”
A delay line is secured to a beam transmitting portion of the ultrasound probe to reduce the effects of the ultrasonic near field and eliminate the dead zone caused by the initial ultrasound pulse. Known ultrasound probes include a hard plastic delay line secured to the transducer. Because the delay line is hard and rigid, a liquid coupling agent, such as water, is used between the delay line and the transducer to effectively couple the transducer to the structure.
Typically, delay lines are flat or otherwise conform to a signal-emitting surface of the transducer. If a signal-emitting surface of the transducer is flat, the delay line is also flat. If a signal-emitting surface of the transducer is curved, the curvature of the delay line is typically the same as the surface of the transducer to ensure a constant sound path from the transducer face to the front surface of a structure.
However, during operation, pockets of air may become entrapped between the delay line and the structure that is being examined. The entrapped air, which may be in the form of air bubbles, affects the ability of an ultrasound system to properly display echoes from the structure. The entrapped air may cause image artifacts, reduce image quality, and otherwise hinder accurate analysis of the structure.
Accordingly, a need exists for an assembly, system, and method that eliminates, minimizes, or otherwise reduces air entrapment between an ultrasound probe assembly and a structure that is being examined. Further, a need exists for a method of shaping and focusing a beam beyond the capabilities of single element transducers.